bgpd: Initialise timebuf arrays to zeros for dampening reuse timer

bgpd: Initialise timebuf arrays to zeros for dampening reuse timer

Avoid having something like this in outputs:

Before:
```
munet> r1 shi vtysh -c 'show bgp dampening damp'
BGP table version is 10, local router ID is 10.10.10.1, vrf id 0
Default local pref 100, local AS 65001
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          From             Reuse    Path
 *d 2001:db8:1::1/128
                    2001:db8::2      (null) 65002 ?
 *d 2001:db8:2::1/128
                    2001:db8::2      (null) 65002 ?
 *d 2001:db8:3::1/128
                    2001:db8::2      (null) 65002 ?
 *d 2001:db8:4::1/128
                    2001:db8::2      (null) 65002 ?
 *d 2001:db8:5::1/128
                    2001:db8::2      (null) 65002 ?

Displayed  5 routes and 5 total paths

munet> r1 shi vtysh -c 'show bgp dampening flap'
BGP table version is 10, local router ID is 10.10.10.1, vrf id 0
Default local pref 100, local AS 65001
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          From            Flaps Duration Reuse    Path
 *d 2001:db8:1::1/128
                    2001:db8::2     2    00:03:10 (null) 65002 ?
 *d 2001:db8:2::1/128
                    2001:db8::2     2    00:03:10 (null) 65002 ?
 *d 2001:db8:3::1/128
                    2001:db8::2     2    00:03:10 (null) 65002 ?
 *d 2001:db8:4::1/128
                    2001:db8::2     2    00:03:10 (null) 65002 ?
 *d 2001:db8:5::1/128
                    2001:db8::2     2    00:03:10 (null) 65002 ?

Displayed  5 routes and 5 total paths
```

After:

```
munet> r1 shi vtysh -c 'show bgp dampening damp '
BGP table version is 10, local router ID is 10.10.10.1, vrf id 0
Default local pref 100, local AS 65001
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          From             Reuse    Path
 *d 2001:db8:1::1/128
                    2001:db8::2      00:00:00 65002 ?
 *d 2001:db8:2::1/128
                    2001:db8::2      00:00:00 65002 ?
 *d 2001:db8:3::1/128
                    2001:db8::2      00:00:00 65002 ?
 *d 2001:db8:4::1/128
                    2001:db8::2      00:00:00 65002 ?
 *d 2001:db8:5::1/128
                    2001:db8::2      00:00:00 65002 ?

Displayed  5 routes and 5 total paths

munet> r1 shi vtysh -c 'show bgp dampening flap'
BGP table version is 10, local router ID is 10.10.10.1, vrf id 0
Default local pref 100, local AS 65001
Status codes:  s suppressed, d damped, h history, * valid, > best, = multipath,
               i internal, r RIB-failure, S Stale, R Removed
Nexthop codes: @NNN nexthop's vrf id, < announce-nh-self
Origin codes:  i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

   Network          From            Flaps Duration Reuse    Path
 *d 2001:db8:1::1/128
                    2001:db8::2     2    00:00:15 00:00:00 65002 ?
 *d 2001:db8:2::1/128
                    2001:db8::2     2    00:00:15 00:00:00 65002 ?
 *d 2001:db8:3::1/128
                    2001:db8::2     2    00:00:15 00:00:00 65002 ?
 *d 2001:db8:4::1/128
                    2001:db8::2     2    00:00:15 00:00:00 65002 ?
 *d 2001:db8:5::1/128
                    2001:db8::2     2    00:00:15 00:00:00 65002 ?

Displayed  5 routes and 5 total paths
```

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>
(cherry picked from commit c39506d80f3e42059e00e562f0c5b376a5246ddd)